Boy or girl: Can you choose naturally?

Folklore is full of creative, do-it-yourself suggestions for predetermining your baby's sex. For example, women should eat more meat and salty foods to get a boy, or couples should make love with the man on top during a full moon to get a girl. Most of these methods are harmless, if you want to try them just for fun. But there's no scientific evidence that any of these methods are effective.

One popular natural method for gender selection is called the Shettles method. It is based on the premise that intercourse timing can influence the sex of your baby. For instance, couples are supposedly more likely to have a boy if they have intercourse as close to ovulation as possible — when conditions in the vagina are apparently more favorable for the "Y" (male) sperm. Proponents of the Shettles method claim it is up to 75 percent effective. But many experts dispute this.

There are effective medical techniques for selecting the sex of your child using in vitro fertilization. However, these techniques are usually reserved for the prevention of sex-specific genetic disorders, such as hemophilia and Duchenne's muscular dystrophy, which primarily affect males. Many doctors' groups are opposed to the use of gender selection for nonmedical reasons.